1. Field of The Invention
This invention relates to a device for detecting an amount of movement and a method of detecting an amount of movement, and more particularly, to a device and a method which respectively hierarchize two image data different in time when detecting the movement of an image and then detect the amount of movement.
2. Description of The Related Art
It is known in the processing of motion pictures to employ the direction of movement and the magnitude (or speed) of an object in the images different in the amount of movement (motion vector), i.e., time. The amount of movement is used, for example, in the motion compensation interframe coding in high-efficiency picture coding or in the movement-based parameter control of a television noise reduction device using an interframe time regional filter. As an amount-of-movement detection method of obtaining an amount of movement of this image, there has been employed a block matching method (Japanese Patent Publication No. 54-124927).
In this block matching method, an image is first divided into blocks comprising several suitable pixels. Between the image data blocked in this way and a search region in which the image data of a screen different in time is blocked to search for a region that the blocked image data have moved, the two image data are evaluated at a pixel unit with a predetermined evaluation function, and the amount of movement between the two sets of blocked image data is detected by obtaining an optimum value giving the minimum evaluation value. Thereby, the amount of movement of an image can be detected with a high degree of accuracy.
However, it is necessary, in the block matching method to completely search all of the search regions, which becomes a range of detection, over all of the pixels of a block of an object of detection and to obtain the difference. For this reason, there is the problem that the amount of calculation for detecting an amount of movement becomes large, the device itself is increased in size, and the time of operation becomes longer.